Yes, 6 Covered Bridges plus a Pony Box Bridge (only the trusses are covered). All of which are in Pennsylvania. Also great views of the Delaware River from the Bull's Island Bridge. This is a unique cycling experience for NYC riders in region, riding surface, landscape and local architecture.
Vertical gain on Ridewithgps might be inflated, although there is definite climbing.
Stop for food/fluid in Carversville, PA: Max Hansen country store.
In season, public restrooms open on Bull's Island.
Consider stopping on the return in Lambertville for dinner.
Trains from NYC Penn Station run hourly, riding time 90 minutes each way. 2 bikes can be carried on either end of the double decker train cars, flipping seats up. You can secure your bikes with thin rope, sitting on seats across the aisle. Train begins at NYC Penn and ends at Trenton so you will not be rushed on and off. NJ Transit does not have bike permits; one less hassle!
Online NJ Transit schedule: http://www.njtransit.com/sf/sf_servlet.srv?hdnPageAction=TrainTo
Restrooms at Trenton Transit Center, either end of station.
The towpath surfaces are gravel. It is friendly to road bikes but wider tires are a nicer option if you have them. I'm not sure I would do this with less than a 20 mm tires. Paceline riding possible but need for attention to other users on towpaths as well as care in slowing and estimating headroom when passing under bridges on the Delaware Canal path. A number of these underpasses have blind spots for oncoming user traffic that demand pause.